Nowadays, in cell phones or other handheld devices, micro cameras which has a much smaller size than a common camera module, are used more and more widely. Generally, a micro camera module includes an image sensor, one or more image processing chips and a focusing lens system. A fixed focusing lens system is mainly used in a micro camera which is integrated in a cell phone or other handheld devices due to its size and manufacturing cost limitation.
In practice, micro focusing devices have become a development trend and research focus. In a current automatic focusing camera, a voice motor technology of a focal length is adjusted by the retraction and repulsion of magnetism, where a voice motor technology device has a large size and high power consumption, and the adjusting rate is slow. Therefore, to be assembled in a micro camera module conveniently, a focusing device should have a small size, low power consumption and low manufacturing cost.
How to realize an automatic focusing function in a micro camera module which has a very small size, low power consumption and low manufacturing cost has become a problem exigent to be solved.